https://forums.macrumors.com/thread...

How could this even work remotely? Like wtf

Not sure, but cloud is decentralized and thus there is a lot of possibilities.

(at least that's how I understand the problem after skimming through the forum thread)

E.g. chunked transfer via HTTP and the "source" chunks do not come from one server alone, but different server regions.

If the server regions are not synchronized, you get now chunks of different files...

Server region as in different data centers

Creepy

To me it looks like it might be a corrupted memory access. What's seen could be video frames or pictures of other people using the service recently and the memory not being initialized properly. It seems a buffer is prepared for the video download, but instead what is dumped might be old data and system garbage. For all we know most of those frames are data un-aligned frames of other videos or perhaps even sensitive profile information :^)